Sunshade



H. NERWIN Nov. 23, 1943.

SUNSHADE Original Filed March 9, 1939 m M Z A n 6 w a fi W U Q 4 p g L 7 mm E Z,

Patented Nov. 23, 1943 I SUNSHADE Hubert Nerwin, Dresden-Reick, Germany; vested in the Alien Property Custodian Original application March 9, 1939, Serial No. 260,738. Divided andthis application June .23,

1941, Serial No. 399,283.

3 Claims.

away in its carrying case it is necessary to remove the sunshade from the camera.

It is the principal object of the invention to provide a sunshade which need not be removed from the camera when the same is to be folded together or packed away. According to the invention the sunshade is provided with a telescopic tubular member of such a size that it may be moved from its extended operative position axially rearwardly over the lens mount, so that it surrounds the lens mount in its inoperative position.

Another object of the invention is to provide the sunshade with a supporting member adapted to be secured to the front end of the lens mount and on which the tubular member is adjustably secured so as to be supported by said member in operative and inoperative position.

Another object of the invention is to provide an adjustable sunshade whose projection beyond the lens is adjustable in accordance with the setting of the variable diaphragm of the lens.

Other objects of the invention will become apparent from the following description with reference to the accompanying drawing which illustrates a few embodiment of the invention.

In the drawing:

Figure 1 is an elevation view, partly in section of a photographic objective provided with a sunshade, in extended or operative position.

Figure 2 illustrates the sunshade in its inoperative position on the photographic objective, and

Figure 3 is .a front view of the sunshade illustrated in Fig. 1 with a portion broken away.

Referring to Fig. 1, the sunshade comprises In Germany May 9,

a supporting ring I adapted to be secured to provided at the front end of the mounting ring 6 for the front lens 1 of the photographic objective.

A tubular member 3 is connected with the outer circumference of the supporting ring I by means of a thread l5. Preferably a multiplex thread I5 having a high pitch is employed, so that the tubular shade member 3* can be moved by a relatively short rotative movement from its extended operative position, illustrated in Fig. 1 to its retracted inoperative position illustrated in Fig. 2.

The ends of the tubular member 3' have rings I6 and ll respectively attached thereto, each of which is provided with an inwardly extended flange I8 and I9 respectively, which form stops for limiting the axial movement of the tubular member 3 with respect to the supporting ring I.

In order to adapt the sunshade for the attachment of a color filter or polarizing filter, the supporting ring I- is provided with an interior thread 20 for receiving an exteriorly threaded mounting ring 22 in which aiilter 23 is secured.

It is also possible to provide the light filter with a mounting ring which is clamped between the outer end of the tubular member 3 and the flange 3 of the ring 16, in which cases the ring it holds the mounting ring in position.

When the aperture of the lens diaphragm is reduced then the conical light beam of the objective is also reduced with respect to a point located at a predetermined distance from the picture plane. Therefore, a sunshade having a certain diameter and a certain axial length would be absolutely correct only for a predeterminedaperture of the lens diaphragm. It appears obvious, that if the sunshade is correctly dimensioned for the full aperture of the lens system, that the axial length of the sunshade could be longer when the aperture of the lens diaphragm is reduced.

The present invention lends itself admirably for adjusting the axially movable shade-forming tubular member ll in accordance with the setting of the diaphragm aperture, so that the front end of the sunshade can be adjusted to such a position that it just permits the passage of the conical light beam. In order to adjust the extension of the sunshade in accordance with the setting of the lens diaphragm the outer end face of the supporting ring I is provided with a diaphragm scale 25 (Fig. 3) and the rotatable tubular member 3 is provided with an index which may be brought opposite any scale division of the scale 25. when the lens diaphragm is V adjusted to a certain aperture, which is indicated by the diaphragm scale 21 on the diaphragm adjusting ring 28 of the lens mount 2, the sunshade may be adjusted to its most favorable position byrotating the tubular member 3' until its index, formed in the present instance by an axial groove 30 on the inner wall of the tubular member 3*, is brought opposite a similar scale division of the scale 25 on the supporting ring I What I claim as my invention is:

1. A sunshade for a photographic objective, including a tubular member provided at its inner wall with a thread, a supporting ring adapted to be attached to the mount 01 the photographic objective and having an exterior thread meshing with said interior threadof saidtubular member, whereby upon rotation of said tubular member-the same is axially displaced relatively to said supporting ring, said tubular member being thus adapted to be adjusted into an extendedoperative position andinto a retracted inoperative position, in said inoperative position said tubular member surrounding the photographic objective mount to which said supporting ring is attached, and an inwardly extending flange on each end of said tubular member for arresting the combined rotative and axial movement of the same by engaging either end face of said supporting ring when the tubular member reaches either its extended or retracted position.

2. In combination with a photographic ob- Jective having a lens mount provided with a manually rotatable diaphragm adjusting ring, an axially adjustable sunshade, including a tubular member provided at its inner wall with a" thread, a supporting ring detachably attached to said lens mount and having an exterior thread meshing with said interior thread of said tubular member, whereby upon rotation of said tubular member, the same is axially displaced relatively to said supporting ring and said lens mount, said tubular member being thus adapted to be adjusted into an extended operative posltion and into a retracted inoperative position, in said inoperative position said tubular member surrounding the lens mount to which said supporting ring is attached, a diaphragm scale on said supporting ring, and means on said tubular member forming an index cooperating with said diaphragm scale, whereby uponrotation of said tubular member said index indicating at any one instant the lens diaphragm aperture ior which the sunshade has been adjusted.

3. In combination with a photographic ob- :Iective having a lens mount provided with a manually rotatable diaphragm adjusting ring, an axially adjustable sunshade, including a tubular member provided at its inner wall with a thread, a supporting ring detachably attached to said lens mount and having an exterior thread meshing with said interior thread of said tubular member, whereby upon rotation of said tubular member the same is axially displaced .relatively to said supporting ring and said lens mount, said tubular member being thus adapted to be ad- :Iusted intoan extended operative position and into a retracted inoperative position, in said inoperativev position said tubular member surrounding the lens mount to which said supporh ing ring is attached, a diaphragm scale on the outer end face of said supporting ring, and an axial groove on the inner wall 0! said tubular member, said axial groove forming an index cooperating with said diaphragm scale for indicating at any one instant the lens diaphragm aperture for which the sunshade has been adjusted.

HU'BERT NERWIN. 

